The utility model provides a fixed bed pressure gasification system relates to gasification technical field, for methane content in the coal gas of solving the output is high, to the great problem of system's productivity influence. Fixed bed pressure gasification system includes: gasification reaction ware, methane conversion device, coal gas waste boiler, washing saturator and grey water treatment system, the air inlet of methane conversion device is linked together with the gas outlet of gasification reaction ware, and the top of methane conversion device is provided with gasifying agent inlet, and the gasification agent that gets into the methane conversion device via gasifying agent inlet includes oxygen, coal gas waste boiler is linked together with the gas outlet of methane conversion device, the washing saturator is linked together with coal gas waste boiler, grey water treatment system is linked together with gasification reaction ware, coal gas waste boiler and washing saturator respectively. Fixed bed pressure gasification system can effectively solve the shortcoming that the gaseous methane content of output is high, organic matters such as tar are smugglied secretly to coal gas.